Case shift mechanism for typewriters and like machines



HELMOND w. F. 7 CASE SHIFT MECHANISM FOR TYPEWRITERS AND LIKE MACHINESFiled Dec.. 8, 1949 INVENTOR.

g 3 g WILL/AM EHELMOND ATTORNEY Patented Oct. 2, I951 CASE SHIFTMECHANISM FOR TYPE- WRITERS AND LIKE MACHINES William F. Helmond,Clinton, Conn., assignor to Underwood Corporation, New York, N. Y., a

corporation of Delaware Application December 8, 1949, Serial No. 131,824

3 Claims. 1

This invention relates to case-shift mechanisms for typewriters, and hasreference particularly to the stops for arresting the shiftable memberof the typewriter in either case position.

The invention is in the nature of an improvement in the case-shift stopdescribed and claimed in the Helmond patent, No. 2,349,723, issued May23, 1944, an object being to provide a stop element which in itscooperative function in the case-shift mechanism will assure quieter andmore accurate limiting of case-shift movement.

Stop elements subjected to the frequent impact incident to case-shiftingand constructed entirely or in substantial part of resilient materialare apt to deteriorate or otherwise become deformed, and thus requirefairly frequent replacement to maintain accurate case-shift. A furtherobject of the invention is to provide a stop element which may beentirely devoid of resilient material such as rubber and the like, andyet will afford operating characteristics superior to stops comprisingsuch materials.

Other objects will be in part obvious and in part particularly pointedout as the following description of a preferred embodiment of theinvention proceeds.

In the drawings: 7

Fig. 1 is a fragmentary elevational view of a typical case-shiftmechanism embodying the improved stop element of the invention,

Fig. 2 is a side elevational view taken on a plane indicated at line 22of Fig. 1,

Fig. 3 is a perspective view of the case-shift stop element, and,

Fig. 4 is an exploded view of said element showing the component partsthereof.

Referring to the drawings, the case-shift mechanism embodying theinvention as illustrated is substantially similar to that shown anddescribed in said Patent No. 2,349,723. A segment frame 5 carries atype-bar segment 6 for pivotal support of a series of type-bars 1 havingupper-andlower case type adapted to strike a platen 8 upon shifting theframe 5 to either case position. The segment frame 5 is mounted forcase-shift movement on the main frame of the typewriter, of which oneside member 10 is shown. At its upper region the segment frame hasroller-bearing units II, and at its lower part is guided by arms 12 of arockable shaft l3 pivoted on the main frame. Case-shift movement of thesegment frame 5 is actuated by the usual shift lever, not shown,operatively connected to said frame by a link I4. A spring l5 yieldablyholds the segment frame and type-bar basket in the normal, that islower-case position.

A stud l6 projecting laterally from the segment frame 5 provides pivotalattachment to said frame for the rock shaft arms l2 and extends beyondsaid arms to provide a bearing I! on which a stop element, generallyindicated at [8, is rotatably carried. At each limit of case-shiftmovement the stop element l8 engages confronting counterstops 20, eachadjustably carried on the main-frame side member ID. This side memberhas a cut-out 2| from which lugs 22 are bent inwardly, each lug beingthreaded to receive the screw shank of one counterstop 20. The head ofeach counterstop presents a broad face for engagement with the stopelement 18 and its edge may be knurled for convenience in adjusting thecounterstops to the desired positions which determine the alignment ofthe upper and lower-case type with the typing line.

As shown best in Figs. 3 and 4, the stop element IB comprises ablock-like base or core member 23, a fabric sleeve 24 and a tensionspring 25 or other suitable means for tensioning the sleeve so that itclosely fits the core and is pressed firmly against the upper-and-lowerfaces 26, 21 thereof. These faces of stop element l8, with the portionsof sleeve 24 overlying same, cooperate respectively with thecounterstops 20 in limiting case-shift movement. In the preferredembodiment shown, the core 23 is a hollow box-like or tubular structureof rectangular cross section, open at each end. The tubular structure 23may be formed for example by bending a fiat strip of metal or similarmaterial into that form as shown and, beside the top and bottom wallshaving the faces 25, 21, providesside walls 28. These side walls of core23 each have a centrally disposed aperture 30 fitting the stud bearingI! and therewith constitute a rockable mounting for the stop element I8on the case-shiftable segment frame 5.

At one end of the core 23 the side walls 28 are extended to projectbeyond the adjacent edges of the top and bottom walls 26, 27 to providelugs 3| which serve as shown in Fig. 3 to hold the fabric sleeve 24 fromlateral displacement on the core. The opposite end of each side wall 28has a hole to receive a hooked end of the spring 25, the free length ofsaid spring between its hooks being somewhat shorter than the spacingbetween the walls 2! so that the spring 25 is under a slight tensionwhen installed.

For best results the sleeve 24 is made up of a closely woven, relativelythin, fabric material such as billiard cloth. Other materials, forexample a good grade of sheet felt capable of withstanding the slighttension applied to the sleeve by spring 25, may also be used. A minimumthickness of the material for the sleeve 24 is preferable in order tominimize the extent to which the material is compacted incident toarresting case-shift movement; for which reason billiard cloth ispreferable. However, a somewhat thicker sheet material such as felt maybe suitable providing the, same is closely felted so as to assure aminimum of compressibility under the pressure of case-shift arrest.

Although the preferred construction of the core 23 takes the form of abox-like or tubular structure, the same may be modified somewhat. Forexample, the core 23 may be formed of a solid block of rigid materialhaving a bore such as at 30 and having a recess at one end to allow thefabric sleeve 24 to be tensioned so as to closely fit the core underinfluence of a suitable ten.- sioning means such as spring 25. Further,although the lugs 3| are desirable, same may be omitted, the tension ofsleeve 24 being depended on tov maintain it frictionally against lateraldisplacement on core 23.

The manner of assembling the parts 23, 2:2 and 25 of the stop element 18is shown in Fig. i. The sleeve 2 is of, such girth as to be readilyinsertable. over the core 23, being passed with out excessive stretchingover the side lugs 3!. With the sleeve thus in place the hooked ends ofspring. 25 are engaged in the smaller holes of the. side walls. 28, withthe. result that the body of the spring presses itself against theportion of sleeve 24 straddling the stop end be tween walls 25, 27. Thehooked ends are formed on the spring 25 in such manner that when thespring is, tensioned between the side walls 28 the coiled portion of thespring is substantially flush with the edges of the side, walls, thuscausing the adjacent area of sleeve 24 to be pressed into the hollowcore as clearly shown in Fig. 3.

In the embodiment of the invention illustrated, the improved stopelement is shown in a typewriter of' the segment-shift or basket-shiftkind wherein the shiftable member is the type-bar segment frame. It willbe evident, however, that the invention is not limited to such kinds oftypewriters but may be embodied in platen-shift type-writers as well.

I claim:

1. In a case-shift limiting means having two confronting counterstops, astop element comprising a generally cubical core of rigid material andhaving opposite faces for cooperation respectively with thecounterstops, a sleeve of fabric material surrounding said core so as tooverlie the. opposite faces and two ends, of said core, at least one ofsaid core ends having a recess, and a tension spring straddling saidrecess to depress the adjacent sleeve portion into the recess andthereby tension the sleeve into firm contact with the opposite faces ofsaid core.

2. In a case-shift: limiting means having two confronting counterstops,a stop element comprising a core composed of a metal tube of rectangularcross. section, the top and bottom walls of said tube presenting outerfaces for cooperation respectively with the counterstops, at least onetube end being open, a sleeve of fabric material surrounding said. coreover said faces and said tube ends, and a tension spring stretchedbetween the sidewalls of the tube at said open end,, the arrangement ofsaid spring being such as to; press the adjacent sleeve portion intosaid open; end and thereby tension the sleeve into firm contact'with theouter faces of said core.

3. In a case-shift limiting means having two confronting. counterstops,a stop element comprising a, box-like hollow core, having an open endand having opposite. faces for. cooperation respectively with thecounterstops, a sleeve of fabric material surrounding said core so, asto overlie, the, opposite faces and two ends of said core... and spring,means acting on the sleeve portion straddling, the. open core end todraw said portion inwardly of the. core and thereby cause the sleeve tofirmly engage the opposite faces of said core.

WILLIAM F. HELMQND.

REFERENCES CITED The following. references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 882,058 Fox Mar. 1'7, 1908946,920 Nichols Jan. 18, 1910 986,246 Tone Mar. 7, 1911 2,349,723Helmond May 23, 1944

